Maybe. Story at "Extreme Tech", which is either extreme, or tech, but not both?
There are two enormous provinces of unusual rock that sit at the bottom of the mantle, just above the Earth's core. One of them is located underneath Africa and one is under the Pacific Ocean. They're called Large Low Shear Velocity Provinces (LLSVPs) and they may shape hotspot formation and volcanic activity across the globe.
The LLSVPs are areas where seismic shear waves propagate much more slowly. They extend laterally for thousands of miles (we think), and they may be up to 1,000km "tall." Geologists have considered a variety of potential explanations for the origin of the LLSVPs, and now a team has put forth a new argument: The LLSVPs may represent the remains of Theia, the protoplanet thought to have smashed into the world some 4.5 billion years ago, creating the Moon. There are a number of hotspots around the world associated with the margins and boundaries of the LLSVPs:
[...] Qian Yuan, a Ph.D. student in geodynamics at Arizona State University (ASU), presented his hypothesis on the topic at the Lunar and Planetary Science Conference.
[...] If the LLSVPs or ultra-low-velocity zones prove to be of extraterrestrial origin, it would mean the planetesimals that helped form the Earth have continued to shape its geology ever since. It's one thing to know the Moon was created in an impact some 4.5 billion years ago, and another to imagine that some of the core of the planetesimal that shaped our entire Earthly existence might still exist itself, trapped below an ocean of liquid rock.
One, of course, is in the Pacific, close to being between Australia and New Zealand, where being Ancient, it sleeps.
Thesis Paper:
Q. Yuan, M. M. Li, S.J. Desch and B.Ko, GIANT IMPACT ORIGIN FOR THE LARGE LOW SHEAR VELOCITY PROVINCES, Arizona State University, School of Earth and Space Exploration.
(Score: 2, Interesting) by Anonymous Coward on Wednesday March 31 2021, @11:41AM
Well, consider that we were already reasonably sure that, after the impact, the majority of Theias and Protoearths combined masses didn't make it any further than the moon.
So we more or less also knew that Theias molecules were still somewhere around, doh.
The surprising, new idea here is that Theia is still around in one or two pieces, not ground into molecules and super-stirred for 4.5 billion years.
Which doesn't make the news any less fine, mind you!
(Score: 2) by Mojibake Tengu on Wednesday March 31 2021, @12:15PM (2 children)
It is extreme tech if both collided planetary cores are actually machines.
Rust programming language offends both my Intelligence and my Spirit.
(Score: 0) by Anonymous Coward on Wednesday March 31 2021, @01:55PM
Yes, true, but we can't in all honesty claim to be a Kardashev 2 civilization while at the same time not even realizing the *existence* of the machinery (much less mastering its usage) for several eons ;-)
(Score: 0, Redundant) by khallow on Wednesday March 31 2021, @02:54PM
"IF".
(Score: 3, Interesting) by VLM on Wednesday March 31 2021, @02:38PM
The old solution was subducted ocean plates from the supercontinent Pangaea got squooshed under the surface and there they sit until being fully stirred in.
So the new puzzle is if this is an impact, then "something else" happened to the subducted plates, so it'll be interesting to see that new theory.
Could be a mix, some from sqooshed ocean plates and some from impacts.